Try parallel builds

Author: alan-george-lk

AGENTS.md

@@ -107,6 +107,9 @@ Updates to ./build.sh and ./build.cmd should be accompanied by updates to this f
 ./build.sh clean-all          # Full clean (C++ + Rust targets)
 ```
 
+The build scripts pass an explicit job count to `cmake --build --parallel`. Set
+`CMAKE_BUILD_PARALLEL_LEVEL` to override the default detected logical CPU count.
+
 **Requirements:** CMake 3.20+, C++17, Rust toolchain (cargo), protoc. On macOS: `brew install cmake ninja protobuf abseil spdlog`. On Linux: see the CI workflow for apt packages.
 
 ### SDK Packaging

README.md

@@ -86,6 +86,9 @@ Using build scripts:
 .\build.cmd release-all       # Build Release with tests + examples
 ```
 
+The build scripts pass an explicit job count to `cmake --build --parallel`. Set
+`CMAKE_BUILD_PARALLEL_LEVEL` to override the default detected logical CPU count.
+
 ### Windows build using cmake/vcpkg
 ```bash
 cmake -S . -B build -DCMAKE_TOOLCHAIN_FILE="$PWD/vcpkg/scripts/buildsystems/vcpkg.cmake"  # Generate Makefiles in build folder

build.cmd

@@ -7,6 +7,7 @@ set "BUILD_TYPE=Release"
 set "PRESET=windows-release"
 set "LIVEKIT_VERSION="
 set "CMAKE_EXTRA_ARGS="
+set "BUILD_PARALLEL_JOBS="
 
 REM ============================================================
 REM Auto-detect LIBCLANG_PATH if not already set
@@ -214,8 +215,17 @@ if errorlevel 1 (
 goto build_only
 
 :build_only
-echo ==^> Building (%BUILD_TYPE%)...
-cmake --build "%BUILD_DIR%" --config %BUILD_TYPE%
+if not defined BUILD_PARALLEL_JOBS (
+    if defined CMAKE_BUILD_PARALLEL_LEVEL (
+        set "BUILD_PARALLEL_JOBS=%CMAKE_BUILD_PARALLEL_LEVEL%"
+    ) else if defined NUMBER_OF_PROCESSORS (
+        set "BUILD_PARALLEL_JOBS=%NUMBER_OF_PROCESSORS%"
+    ) else (
+        set "BUILD_PARALLEL_JOBS=2"
+    )
+)
+echo ==^> Building (%BUILD_TYPE%) with %BUILD_PARALLEL_JOBS% parallel jobs...
+cmake --build "%BUILD_DIR%" --config %BUILD_TYPE% --parallel "%BUILD_PARALLEL_JOBS%"
 if errorlevel 1 (
     echo Build failed!
     exit /b 1

build.sh

@@ -161,14 +161,39 @@ configure() {
   fi
 }
 
+detect_parallel_jobs() {
+  if [[ -n "${CMAKE_BUILD_PARALLEL_LEVEL:-}" ]]; then
+    echo "${CMAKE_BUILD_PARALLEL_LEVEL}"
+    return
+  fi
+
+  local jobs=""
+  if command -v getconf >/dev/null 2>&1; then
+    jobs="$(getconf _NPROCESSORS_ONLN 2>/dev/null || true)"
+  fi
+  if [[ -z "${jobs}" || ! "${jobs}" =~ ^[0-9]+$ || "${jobs}" -lt 1 ]]; then
+    if command -v sysctl >/dev/null 2>&1; then
+      jobs="$(sysctl -n hw.ncpu 2>/dev/null || true)"
+    fi
+  fi
+  if [[ -z "${jobs}" || ! "${jobs}" =~ ^[0-9]+$ || "${jobs}" -lt 1 ]]; then
+    jobs="2"
+  fi
+
+  echo "${jobs}"
+}
+
 build() {
-  echo "==> Building (${BUILD_TYPE})..."
+  local parallel_jobs
+  parallel_jobs="$(detect_parallel_jobs)"
+
+  echo "==> Building (${BUILD_TYPE}) with ${parallel_jobs} parallel jobs..."
   if [[ -n "${PRESET}" ]] && [[ -f "${PROJECT_ROOT}/CMakePresets.json" ]]; then
     # Use preset build if available
-    cmake --build --preset "${PRESET}"
+    cmake --build --preset "${PRESET}" --parallel "${parallel_jobs}"
   else
     # Fallback to traditional build
-    cmake --build "${BUILD_DIR}"
+    cmake --build "${BUILD_DIR}" --parallel "${parallel_jobs}"
   fi
 }